Toyota Not Following Everyone Else With Small Turbo Engines, Sticking With Large Displacement Engines

will we see a 6L+ atkinson cycle iForce in the tundra? haha

Small displacement + turbocharging doesn't pan out for better efficiency. It never did and it still hasn't. The reason is simple... by going from a 2.0L I4 to a 1.4L I4 you haven't changed the frictional losses that much because you still have the same number of valves, guides, followers, pistons, rods, etc. The main efficiency gains come from having smaller cylinders working at bigger throttle openings which allows the engine to operate at a higher effective compression -- because larger throttle openings equals lesser vacuum and squishing less vacuum equals higher effective compression. But turbocharging mandates an ~2 point reduction in compression ratio while providing no charge density improvements at cruise. This cancels out much of the efficient gains from displacement loss.

The best non-hybrid efficiency is actually achieved with a large displacement Atkinson Cycle engine with least amount of camshafts, valves and cylinders. If you want the most fuel efficient 140hp you'll use a 2.5L 3-cylinder engine with 17.0:1 static compression and a 70% Atkinson cycle cam for a 11.9:1 effective compression @ peak volumetric efficiency. You'll use a single overhead cam or a in-block cam with roller followers/lifters. You'll use 2 valves per cylinders. And, you'll use direct injection. Apart from DI, you'll basically do the exact opposite of what many automakers are doing.

In the end, 1.4L Turbo, 2.0L NA and 2.5L Atkinson engines probably have approximately the same output. The 2.5 Atk has the best fuel efficiency whereas the 1.4T has the highest cost and most reliability concerns. The 1.4T is only useful as so far as to take advantage of various countries' displacement tax laws to lower the new car and annual taxes. Whether this is significant depends on the country.